They’re getting ready for more than just a concert: The group is part of an unprecedented, one-day fundraising effort on Sunday by dozens of theaters across the nation and some abroad to present a menu of 10-minute songs and plays.

Sunday marks the one-year anniversary of when a monstrous earthquake triggered a tsunami that roared across Japan’s coast, leaving nearly 20,000 people dead or missing, leaving hundreds of thousands homeless, and sparking the worst nuclear crisis the world had seen in a quarter century.

American and Japanese theater veterans including Doug Wright, Richard Greenberg, Suzan-Lori Parks, Philip Kan Gotanda and Naomi Iizuka have contributed original works, while others, including Edward Albee, John Guare, John Kander and Tony Kushner, have donated older pieces. Japanese playwrights have also contributed their own works that are being translated and will be performed at a later date.

Stephen Sondheim and John Weidman, who teamed up to write “Pacific Overtures,” did something a little different: They combined the songs “Four Black Dragons” and “Next” from their 1976 musical about the Westernization of Japan, added new lyrics and incorporated lines of spoken information about the destruction and recovery.

“There were two or three different parts of `Pacific Overtures’ that Steve and I thought we could pull out and really reshape so that they addressed the terrible results of this tsunami and I think this is the best solution,” said Weidman, who attended the mash-up rehearsal on Tuesday and said he liked what he heard.

“It’s exciting and satisfying to feel that something we created with something completely different in mind so long ago could now be reshaped in order to make this kind of statement,” he said.

About 70 theaters and colleges in America _ ranging from Malone University in Ohio, the McCarter Theatre in New Jersey, Theatre Conspiracy in Florida, Wheaton College in Illinois, and the American Conservatory Theater in California _ have signed up for “Shinsai: Theaters for Japan,” as well as companies in Canada, Turkey and Italy.

Drama clubs, theaters and colleges on Sunday are invited to craft their own fundraising event with their own actors using the 10-minute plays and songs _ downloadable from the Theatre Communications Group’s website _ or using works from their own residential artists.

“You don’t need a lot of high-tech savvy to get the message out. You just need a three-dimensional space, some willing actors and the desire to help,” said Wright, who won a Pulitzer for “I Am My Own Wife” and wrote “A Guide to Japanese Etiquette” for the benefit. “The simple, down-home, threadbare nature of our craft makes it especially useful right now.”

All money raised will go to the Japan Playwrights Association, which will ensure the funds go to repair damaged theaters or rehearsal spaces and be spent on company needs. All the playwrights, actors and organizers are donating their time.

“I think our theater community really believes that we have a responsibility to utilize our art form to change the world if we can,” said Teresa Eyring, the executive director of the group, which connects 700 member theaters and has spearheaded Sunday’s event. “It’s kind of in our DNA to collaborate and to be concerned with the lives of others.”